The most common way of drilling an oil or gas well involves attaching a drill bit to a string of drill pipe and rotating the drill pipe to drill the well. At selected depths, the operator retrieves the drill pipe and runs a string of casing to line the well bore. The operator cements the casing in place. The operator may then continue to drill deeper with the drill pipe and run additional strings of casing.
Another method uses the casing itself as the drill string. The operator employs a casing gripper that will grip the upper end of the casing string to support its weight as well as transmit rotation. The casing gripper is mounted to a top drive. The top drive runs up and down the derrick on one or more guide rails and imparts rotation to the casing gripper.
There are different methods of running casing. One technique involves using casing elevators to support the string of casing and power tongs at the rig floor to make up each new joint of casing to the string of casing. With another method, the operator uses a casing gripper that may be of the same type as employed during casing drilling. By rotating the casing gripper, the operator imparts rotation to a new joint of casing to make up its lower end with the casing string suspended at the rig floor.
When running casing with a casing gripper connected to a top drive, it is known to employ a thread makeup compensator. A thread makeup compensator comprises a telescoping sub that is mounted between the top drive and the casing gripper. The sub extends while the top drive is held at a stationary elevation and rotating the casing gripper to compensate for the casing joint moving downward as its threads are made up to the threads of the casing string.
It is also known in the art to provide data to rig floor personnel concerning the thread makeup of casing joints. This data may include the torque applied to the casing joint while making it up. It has also been proposed to provide data concerning the tension within the casing string. It is also known in the prior art to monitor the rotational speed of the string of pipe in various manners. While thread makeup compensator systems and data sensing of the prior art are feasible, improvements are desired.